Anion exchanger 3 (AE3) is pivotal in regulating intracellular pH across excitable tissues, yet its structural intricacies and functional dynamics remain underexplored compared to other anion exchangers. This study unveils the structural insights into human AE3, including the cryo-electron microscopy structures for AE3 transmembrane domains (TMD) and a chimera combining AE3 N-terminal domain (NTD) with AE2 TMD (hAE3^NTD2^TMD). Our analyzes reveal a substrate binding site, an NTD-TMD interlock mechanism, and a preference for an outward-facing conformation. Unlike AE2, which has more robust acid-loading capabilities, AE3’s structure, including a less stable inward-facing conformation due to missing key NTD-TMD interactions, contributes to its moderated pH-modulating activity and increased sensitivity to the inhibitor DIDS. These structural differences underline AE3’s distinct functional roles in specific tissues and underscore the complex interplay between structural dynamics and functional specificity within the anion exchanger family, enhancing our understanding of the physiological and pathological roles of the anion exchanger family.

阴离子交换剂 3 (AE3) 在调节可兴奋组织的细胞内 pH 值方面至关重要，但与其他阴离子交换剂相比，其结构复杂性和功能动力学仍未得到充分研究。这项研究揭示了对人类 AE3 的结构见解，包括 AE3 跨膜结构域 (TMD) 的冷冻电子显微镜结构以及将 AE3 N 末端结构域 (NTD) 与 AE2 TMD 结合的嵌合体 (hAE3 ^NTD 2 ^TMD )。我们的分析揭示了底物结合位点、NTD-TMD 联锁机制以及对外向构象的偏好。与具有更强大的酸负载能力的 AE2 不同，AE3 的结构（包括由于缺少关键的 NTD-TMD 相互作用而不太稳定的向内构象）有助于其调节 pH 调节活性并增加对抑制剂 DIDS 的敏感性。这些结构差异强调了AE3在特定组织中的独特功能作用，并强调了阴离子交换剂家族内结构动力学和功能特异性之间复杂的相互作用，增强了我们对阴离子交换剂家族生理和病理作用的理解。